What are functional breath tests?
They are the best non-invasive way to investigate a person’s ability to digest certain components of our everyday diet; poor digestion of these components causes abdominal complaints that are often chronic and difficult to recognise.
In particular, they investigate the ability to digest some very common carbohydrates such as lactose, fructose and sorbitol, and also check for bacterial overgrowth in the intestine, which is another cause of many chronic bowel complaints.
The tests, which each involve drinking a glass of water containing a set dose of the carbohydrate being investigated, are simple and completely harmless. No medicine is given, only measured doses of natural substances that we take in every day with our diet. You will be asked to blow into special bags both before and after taking the test substance (at 30, 60, 120 and 180 minutes).
People with diabetes can also take the test, but they should tell the specialist about their condition just before the test starts.
Sophisticated dedicated equipment (a gas chromatograph) then analyses the composition of your breath to check whether (and how much of) certain gases have been produced, indicating that the food has not been properly digested
This is a simple, painless test that looks for H. pylori in the stomach. The patient drinks a solution containing 13C-urea. If the bacterium is present in the stomach, the 13C is found in the exhaled air after thirty minutes. The patient therefore blows into two tubes, before and thirty minutes after drinking the solution. There are no contraindications. Duration of the test: 40 minutes.
This is a breath test to look for lactose intolerance. The fasting patient drinks a solution of water and lactose, then blows into tubes or bags at intervals set by the method. An abnormal amount of hydrogen/methane in the exhaled air allows the diagnosis to be made. Duration of the test: 3 hours.
Preparation:
The test must be done on an empty stomach.
In the seven days before the test the patient must NOT take antibiotics, probiotics or laxatives
The doctor must make sure that the patient does not have significant diarrhoea
On the day before the test the patient must eat only:
BREAKFAST: A CUP OF TEA
LUNCH: a plate of boiled rice dressed with a little oil
DINNER: a steak or boiled fish with salad
From 9 pm on the day before the test the patient MUST fast completely (water may be drunk freely)
From 7 am on the day of the test the patient MUST drink two glasses of water and MUST stay fasting, must not brush their teeth, must not smoke and must not do any physical activity.
These are breath tests that look for abnormal bacteria in the small intestine. In the morning, on an empty stomach, a small amount of glucose or lactulose is given. The patient then blows into a bag at set intervals, and the amount of exhaled gases is measured. A double peak of hydrogen/methane allows the diagnosis to be made. Duration of the test: 3 hours.
These are breath tests that look for abnormal bacteria in the small intestine. In the morning, on an empty stomach, a small amount of glucose or lactulose is given. The patient then blows into a bag at set intervals, and the amount of exhaled gases is measured. A double peak of hydrogen/methane allows the diagnosis to be made. Duration of the test: 3 hours.